The present invention relates to valve actuators, and more particularly, to an automatic valve actuator of the spring operated type for actuating a rotary actuated valve automatically in response to an occurrence of exigent character, such as fire.
It has been known to provide automatic valve actuators for causing automatic actuation of a rotary valve in the event of fire causing melting of a heat-actuated fusible link. Such valve actuators have not been altogether successful in that they either do not permit normal valving or interfere with normal operation of the valve. For example, if the actuator incorporates a spring, such spring may increase the operating force of the valve handle during normal operating conditions by imposing a torque upon the valve actuation shaft.
Salmon U.S. Pat. No. 1,026,884 discloses a fluid shut off apparatus which is simply a valve having an actuating handle with a weight attached thereto, there being a fusible support for maintaining the handle in a position permitting flow through the valve, the fusible support permitting the handle to swing in response to gravity upon sufficient heat. In addition, the arrangement provides for manual release of the handle. However, the latter mechanism precludes normal operation of the valve. Although the fusible mechanism can be released manually to permit manual operation, when this occurs the valve fusible arrangement is no longer operative and protection against fire is not present, until the apparatus is reset with the valve actuating arm once more being maintained in position by the fusible support.
An automatically operable valve is taught by Hasty U.S. Pat. No. 998,507. The apparatus described therein included a fusible joint. In addition, it had the advantage of having provision for applying heat to the fusible joint from a source of electrical current. However, no normal valving operation was provided, the valve disclosed being incapable of providing manual valve operation, that is, the valve element was either open or closed with the closed condition occurring only in response to melting of the fusible joint in response to heat in the environment, as from a fire, or heat supplied by an electrical current.
Arrangements such as the latter effectively require that a separate valve be utilized in conjunction with the automatically actuated valve, if normal valving with manual preselection of the valving function is to be provided. The use of both manual and automatic valving arrangements in such a redundant fashion is expensive and cumbersome and increases plumbing complexity.
In numerous industrial applications, the increasingly more stringent regulations relative to the health and safety of employees, as well as those intended to prevent an environmentally hazardous, destructive condition which may cause pollution, necessitates the provision of fire-safe valves or other arrangements for causing automatic valve actuation in response to various occurrences of exigent character, such as fire, smoke, excessive heat, and various other conditions which may be detected by personnel, or by equipment particularly suited for being responsive to a condition to be monitored.
When existing valving arrangements are desired to be provided with automatic actuation facilities, it is heretofore not been convenient or practical to modify existing valves so as to be actuated automatically. Instead, separate valves having valve actuators integral therewith have been used for this purpose. It has been proposed to simply equip a valve with a spring return and to install a fusible link for causing the valve to remain open unless the link should be mounted, as by excessive heat, thereby permitting the spring loading to return the valve to a closed position.
Botkin U.S. Pat. No. 3,538,929 represents an attempt to provide a valve actuator which permits the valve handle of a conventional rotary actuated valve to be operated in the normal manner. This spring tension is released by a fusible link. This releases a head which rotates so that projections of the head engage projections on the valve operating handle thereby to move the valve to a closed position.
The valve actuator disclosed in the above-identified patent, while providing the advantage of not interfering with normal operation of a valve, has the disadvantage of requiring multiple heat sensitive links of a fusible type which are oriented in a position making them difficult to replace. Additionally, the valve actuating springs and other elements are exposed to the elements and the actuator is not compact, nor is it amenable for being mounted directly to the body of the valve. Additionally, the latter actuator is disclosed as being useful for only closing a valve.
In many installations, it is desirable that the valve not fail shut but rather fail open or fail in an "as was" position, by the latter meaning that the valve is to be automatically actuated so as to return to a condition to which the valve previously has been set, e.g., a partially open or partially closed position.
Another deficiency of valve actuators of the prior art is that they are not amenable to the use of fusible links of various different types, such as electrically actuated as well as fire-sensitive fusible links.
An important object of the invention is the provision of an improved automatic actuator for rotary valves, and particularly the provision of such a valve actuator which provides automatic actuation of a valve without interfering with normal operation of the valve.
A further object of the invention is the provision of such a valve actuator which is of a compact nature and is adapted for being secured to a conventional rotary valve, such as a quarter-turn ball, butterfly or plug valve, for automatic actuation thereof.
A further object of the invention is the provision of such an automatic valve actuator which incorporates an actuating spring but wherein the actuating spring and other important elements are enclosed to protect them from the elements.
Yet another object of the invention is the provision of a valve actuator permitting normal manual or remote service operation of a valve, and although utilizing a thermal link which permits such operation without voiding normal fusible link warranties.
A still further object of the invention is the provision of such a valve actuator which is optionally configurable for providing fail closed, fail open, or fail "as was" modes of operation in response to an exigent occurrence.
An important further object of the invention is the provision of such a valve actuator which will provide valve actuation in response to occurrences such as heat, fire, or electrical signals from a remote location or from a smoke or other detector device.
Among still further objects of the invention may be noted the provision of such valve actuator which may be utilized in connection for valves with sprinkler systems to provide fire protection, which can be utilized to comply with occupational safety and health requirements, to prevent environmental damage, for example, in conjunction with petroleum and gas platform rigs, and which can be utilized to shut off or to maintain the operation of fluid systems in various industrial applications.
Another object of the invention is the provision of such a valve actuator of the type utilizing a fusible link but which, upon separation of the fusible link during fail safe operation precludes the fusible link elements from being thrown from the actuator as dangerous projectiles.
Among additional objects of the invention may be noted the provision of such a valve actuator which is extremely simple, low cost and of configuration having relatively few parts and facilitating low cost and simple manufacture; and which is durable, long lasting and extremely reliable in operation.
Other objects and features will be in part apparent and in part pointed out hereinafter.